Fungal infection has been a common disease which greatly affects health. The incidence of fungal infection in deep tissue and mortality caused therefrom has increased dramatically in the recent decades due to the extensive application of clinical wide-spectrum antibiotics, hormones, anti-tumor drugs, and immunosuppressants, development of large scale organ transplantation operation, spread of AIDS, and even SARS in first half of the year 2003. Highly effective antifungal drugs with low toxicity have been in urgent and great demand. However, there are only a limited number of known clinically available antifungal reagents that can be chosen from, including amphoterlcin B, Ketoconazole, Fluoroconazole, and Itraconazole. In the recent years, research and development of antifungal drugs have been focused on azoles compounds. Multinational pharmaceutical companies have developed these medicaments in clinical use. Voriconazole developed by Pfizer Inc. has been on the international market since the year 2002; Posaconazole developed by Schering-Plough is known to be coming into the market soon. Despite of certain advantages of these newly developed antifungal drugs, they have disadvantages including high toxicity, ineffective towards some fungi, and low bioavailability, thus, they are not able to fully meet the needs of the patients. There still exists the great and urgent demand for developing an effective antifungal drug with high bioavailability and low toxicity.
Coumarin is a lactone of o-hydroxycassia acid which can be found in the plant world of the family of Umbelliferae, Leguminosae, Rueae, Compositae, Saxifragaceae, and Thymelaeaceae as well as in the metabolites of microorganisms, while coumarin can not be found at all in the animal world. Coumarin can be found in all parts of plants in the descending order of richness as fruits>roots and fibrous roots>stems>leaves. About 800 coumarin compounds have been identified since the year 1980.
Furanocoumarin has been used for ages in traditional medicine. The Indian myth bible “Athara Veda” describes the treatment of leukoderma by a paste medicament prepared from the refinement of Psoralea corylifolia tree; ancient Egyptians used Ammi majus to cure vitiligo. In 1838, Kalbrunner was the first to separate furanocoumarin and 5-methoxypsoralen from bergamot (Scott, B. R.; Pathak, M. A.; Mohn, G. R. Mutat. Res., 1976, 39, 29.).
Coumarin compounds have extensive bioactivities. For examples, coumarin compounds can be used as anticoagulant, estrogenic, they have anti-dermal photosensitizing activity, they are antibiotics, vasodilators, molluscacides, anthelmintics, sedatives and hypnotics, analgesics and having hypothermal activity (Soine, T. O. J. Pharm. Sci., 1964, 53, 231; Edelson, R. L. Sci. Am., 1988, August, 68; Dini, A.; Ramundo, E.; Saturnino, P.; Stagno, d'Alcontres, I. Boll. Soc. Ital. Biol. Sper., 1992, Univ. Lodz). Coumarin compounds have been known as the pharmaceutical promiscuity for the extensive bioactivities. (Hoult, J. R.; Paya, M. Gen. Pharmacol., 1996, 27, 713) Coumarin compounds that have significant physiological effects include: aflatoxin having acute hepatotoxicity and carcinogenicity, dicoumarol having anticoagulation (Rocha, L.; Marston, A.; Kaplan, M.; Stoeckli-Evans, H.; Thull, U.; Testa, B.; Hostettmann, K. Phytochem, 1994, 36, 1381); novobiocin and coumermycin A1 having antibiotic activity; some linear furanocoumarins having photosensitivity at the cellular level, which has caused vast interested from biochemists and has been used for assisting in crosslinking of DNA fragments. Structures and physiological activities for some compounds are listed below. (Stud. Nat. Prod. Chem., 2000, 33 (Bioactive Natural Products(Part D), 350.)

Due to their wide-ranging availability in plants and excellent bioactivity, many coumarin compounds have been used for preparing medicaments, which has invoked great interest in chemists, pharmaceutical industry researchers, and biologists.